Kent Beck, et. al.
Business people and developers must work together daily throughout the project (Beck et. al., “The Agile Manifesto,” 2001).
Sanger
“Wikipedia’s self correction process (Wikipedia’s co-founder, Jimmy Wales, calls it ‘self-healing’) is very robust. There is considerable value created by the public review process that is continually going on in Wikipedia–value that is very east to underestimate, for those who have not experienced it adequately. (Sanger, “Wikipedia is wide open,” 2001)
Eric Raymond
“Release early. Release often. And listen to your customers.” (Raymond, “The Cathedral and the Bazaar,” 2000)
“If you treat your beta-testers as if they’re your most valuable resource, they will respond by becoming your most valuable resource.”(Raymond, “The Cathedral and the Bazaar,” 2000)
“Given a large enough beta-tester and co-developer base, almost every problem will be characterized quickly and the fix obvious to someone.” (Raymond, “The Cathedral and the Bazaar,” 2000)
“Release early. Release often. And listen to your customers.” (Raymond, “The Cathedral and the Bazaar,” 2000)
“Treating your users as co-developers is your least-hassle route to rapid code improvement and effective debugging.” (Raymond, “The Cathedral and the Bazaar,” 2000)
“The next best thing to having good ideas is recognizing good ideas from your users. Sometimes the latter is better.” (Raymond, “The Cathedral and the Bazaar,” 2000)
Opening My Masters 